Views: 54 Author: VV Publish Time: 2018-11-12 Origin: Rech Chemical Co. LTD
Chromium is serious metal contaminant. The chromium in cement mainly comes from the raw materials of industrial by-product and the process of burning. Recently, with the increasingly strict requirements in domestic environmental protection, ferrous sulphate is becoming more and more popular in removing Hexavalent Chromium during the production of cement. European cement manufactures purchases a large amount of ferrous sulfate from China every year to reduce hexavalent chromium in cement. However, most of our domestic cement manufacturers use ferrous sulfate solution to remove chromium, which is very costly. Recently, a lots of cement manufactures call us(Rech Chemical Co. LTD,) to find out, How to add ferrous sulfate to remove Hexavalent Chromium in cement manufacturing
The chromium presents in the form of hexavalent in cement. As far as we know, ferrous sulphate as reducing agent in production of cement. The common solutions are to add ferrous sulfate monohydrate granular or powder. Ferrous sulfate monohydrate granular usually added to the grinder together with the cement raw materials. For some manufacturers asked the powder over 300mesh, but the size of ferrous sulfate monohydrate is 80mesh. Another way is to stir ferrous sulphate monohydrate powder with finished cement product.
At the same time, in the add ferrous sulfate, temperature is very important to reduce chrome. such as a water soluble hexavalent chromium content < 0.1 mg/kg of bagged cement at 20 ℃ to 25 ℃, about 50% of the relative humidity can store 6 months, the water-soluble hexavalent chromium content was only 0.2 mg/kg, this is because ferrous sulfate dehydration and reduce reduced chromium solubility.